1. Field of the Invention
The invention relates to an illumination arrangement for a stereo microscope.
2. Description of the Related Art
In stereo microscopy, external incident illumination arrangements in which direct illumination is arranged outside the microscope base body belong to prior art.
Such arrangements can be halogen lamps with reflector mirrors which are fastened to the stereo microscope support, to the pillar or to the stereo microscope base body itself and enable oblique incident illumination.
Cold-light illumination arrangements which are arranged, for example, at the pillar or at the stereo microscope support are known and are constructed, for instance, as flexible or semirigid one-armed or multiple-armed light guides with focusing optics. Without fastening to the stereo microscope base body or to the stand, there are one-armed or multiple-armed, semirigid goosenecks, as they are called, which are fastened exclusively to the cold-light source and can be optionally positioned spatially.
Further, cold-light ring lamps which are attachable to the front area of the stereo microscope are known and available, e.g., as 4-point ring lamps or slit ring lamps in different diameters and radiating angles. All of these external incident illumination arrangements ensure a highly differentiated incident illumination, i.e., the object examined through the stereo microscope can be optimally illuminated corresponding to its surface structure and spatial extension. A disadvantage in these external illumination arrangements is that they sometimes occupy considerable space in the object region, i.e., direct viewing of the object and free space for manipulation is sometimes severely limited.
A further disadvantage in these external illumination arrangements consists in that when the stereo microscope is fastened in special stands (e.g., machine holders, floor or wall stands) and as a result of the free spatial positioning of the stereo microscope which this involves, the light must first always be xe2x80x9ctrackedxe2x80x9d separately (insofar as the illumination arrangement is not fastened to the stereo microscope base body itself). The disadvantages mentioned above can be avoided if the illumination arrangement itself can be successfully integrated in the stereo microscope base body in a suitable manner so as to save as much space as possible.
A number of different suggestions for solving this problem, some of them already published, with the aim of suitably integrating illumination systems directly in optical instruments (for example, in photographic cameras, video cameras, camcorders, microscopes, stereo microscopes, operation microscopes) are known internationally.
In stereo microscopy, internal incident illumination arrangements in which the light is coupled into (coaxial incident light principle) the observation channels via suitable beam splitting elements (prisms, splitter mirrors) inside the microscope base body are known from the prior art. In this connection, light can be generated by a conventional microscope incident light arrangement or via a cold-light source and light guides and can be transported until it is coupled into the observation channels via the above-mentioned beam splitting elements at different locations (e.g., above or below the stereo microscope pancratic or zoom system). Aside from the above-mentioned coaxial illumination arrangements which are fixedly integrated in the stereo microscope base body, there are also modular units which can be arranged, for example, in such a way that they can be divided between the stereo microscope pancratic system and the main objective (e.g., Zeiss telescope type stereo microscope with modular coaxial illumination device and flexible light guide input coupling, light guide connection to Schott cold-light source KL 1500). An advantage in the coaxial illumination arrangement is that the light is xe2x80x9cguided alongxe2x80x9d with the stereo microscope base body and, in case of internal coupling in above the stereoscopic pancratic system, that there is an exact adaptation of the object field during zoom magnification. With internal coupling in below the stereoscopic pancratic system, the size of the illuminated object field is constant and is designed for the maximum object field that can be achieved with the pancratic system. A disadvantage in all of the above-mentioned arrangements with the coaxial incident light principle is the occurrence of strong reflectionsxe2x80x94especially with highly reflective object surfacesxe2x80x94and a resulting deterioration in image contrast through the coupling of light into the observation channels. The various possible arrangements for suppression of reflections with polarizing-optical means (e.g., antireflection device for Zeiss telescope type stereo microscopes) are also prior art. Known reflection suppression arrangements with polarizing-optical means have their own disadvantage in that a considerable reduction in illumination intensity occurs due to the high absorptive power of the at least two polarizing filters that are required. Other internal incident illumination arrangements which are modified from this basic principle and employed in telescope type stereo microscopes use only the front main objective for coupling light into the observation beam paths or into an azimuthal plane of incidence different from the observation channels. In these arrangements which are modified from the basic principle, there also remains the problem of the formation of reflections and elimination thereof with polarizing-optical means. In stereo microscopy, the coaxial incident light principle is preferably applied only with planar or flat specimens (shallow depth of field) because, with this vertical illumination, only a poor contrast or a poor spatial visual impression can be achieved in case of objects with depth of field or objects with surface relief; a substantially improved contrast and spatial impression can be achieved by the shadow effect occurring with oblique illumination. The different internal illumination arrangements working in accordance with the coaxial incident light principle which were described above are used in conventional stereo microscopes (telescope type construction), operation microscopes, in medical equipment with stereoscopic observation (colposcopes, slit lamps) or sometimes in endoscopes.
The laid open application DE 196 40 352 A1, xe2x80x9cInternal Illumination Device and Video Microscope Systemxe2x80x9d, describes an arrangement for coupling in light via beam splitting as is known in conventional brightfield incident light microscopy. Another arrangement provides integration of direct illumination (lamp with reflector mirrors) in a video device; in this case, light is transmitted via light guides into the object space with oblique illumination and there is a repeated coupling of light into the observation channel by light guides via beam splitting (coaxial incident light principle). The proposed integrated illumination arrangements which are known in part from the prior art are directed only to the combination of video microscope system with video equipment.
U.S. Pat. No. 4,783,159, xe2x80x9cOperation Microscopexe2x80x9d, describes a telescope type operation microscope with an integrated internal illumination arrangement for illuminating the operating field. In this connection, the light is principally coupled in between the zoom system (pancratic system) and the main objective. The illumination system which is separately constructed in the operation microscope illuminates the operating field via the following optical elements: light guidexe2x86x92separate zoom systemxe2x86x92projection lensxe2x86x92main objective. Through the use of different optical deflecting elements (reflection prisms), it is possible to illuminate the operating field via the main objective at different locations (axially or extra-axially, as desired), resulting in differentiated illumination of the operating field (e.g., the eye).
Patent EP 0 793 128 A1, xe2x80x9cIllumination Structure in Microscopexe2x80x9d, describes a microscope (stereoscope in a parallel construction/macroscope) in which an internal illumination system is arranged behind the objective. Different arrangements are described by which light can be coupled in behind the objective, for example, on the optical axis of the objective between the observation channels (two pairs) with one illumination channel, between the observation channel pairs with two or more illumination channels, or coupling in light using areas of the observation optics separated by mounts.
Patent DE 39 06 555 A1, xe2x80x9cIncident Light Object Illumination Devicexe2x80x9d, describes an (external) illumination device which is arranged at an observation device and which comprises a plurality of individual light sources (e.g., self-luminous objects, glass fibers or back-lighting diaphragms) which are also switchable individually and which are arranged in an at least two-dimensional array whose center coincides with the optical axis of the observation imaging optics.
The patent xe2x80x9cEpidark Illumination Systemxe2x80x9d DE 39 29 768 A1 describes an Epidark illumination system, preferably for reflected light microscopes, in which light coming from a light source is guided between a sleeve and an objective lens for illuminating an object (arrangement similar to that in incident light darkfield arrangements). A very flat illumination of the object field can be achieved with this ring-shaped illumination arrangement.
Patent EP 0 50 940 A2, xe2x80x9cMicroscope Illuminating Apparatusxe2x80x9d, shows different microscope illumination arrangements for incident light brightfield and darkfield illumination and for transmitted light brightfield and darkfield illumination in which the coupling of light into the illumination-optical systems is carried out by fiber-optics among other means.
Patent DE 19523712 A1, xe2x80x9cStereo Microscopexe2x80x9d, describes a stereo microscope (telescope construction) which has an observation front lens and an illumination lens that are separate from one another. A beam of observation light emitted by an object point is directed parallel by the focusable front observation lens. The illumination lens projects a beam of illumination light onto the object point. A position to be illuminated can be changed corresponding to the movement of an object point by the arrangement/focusing of the observation and illumination lens. It is the object of this special arrangement to achieve illumination which is as coaxial as possible, i.e., to adjust the smallest possible angle between the optical axis of the illumination light and optical axis of the observation light (prevention of reflections).
It is the primary object of the invention to realize the illumination arrangement for stereo microscopes so as to have a minimum space requirement, but in such a way that the basic optical-mechanical construction is influenced only minimally and a bright, homogenous and reflection-free illumination of the maximum visible object field is made possible independent from the position and observation direction of the stereo microscope.
This object is met in an illumination arrangement for a stereo microscope, preferably a Greenough type stereo microscope, comprising at least one, preferably two, illumination channels which are arranged in a plane which is arranged essentially orthogonally with respect to the plane of the two reservation channels, preferably with two light channels in the interior of the microscope housing outside of the observation beam paths, wherein the light channels are guided around the observation optics.
The invention will be explained more fully in the following with reference to the schematic drawings.